In apparent reference to efforts by China’s Amateur Satellite Group (CAMSAT) to coordinate operating frequencies for nine satellites set to launch in early September, the International Amateur Radio Union (IARU) has made it clear that it will not coordinate frequencies do not conform with accepted band plans for all three IARU regions. The IARU has informed CAMSAT CEO Alan Kung, BA1DU, that it was only able to coordinate uplink and downlink frequencies for two of the nine spacecraft (CAS-3/XW-2D and E), but it has not made that letter public. CAMSAT has said it plans to launch the nine satellites, all carrying Amateur Radio payloads, on September 7 or 8.
“The IARU Satellite Adviser, Hans van de Groenendaal, ZS6AKV, and his advisory panel are mandated to coordinate frequencies within the IARU band plans for amateur satellites,” said a public statement released on August 20 by IARU Secretary Rod Stafford, W6ROD. “Coordinated frequencies must comply with band plans that are common to all three IARU regions. Satellites coordinated outside these plans could cause interference to terrestrial amateur operations in other regions.”
The IARU statement suggested that the popularity and high occupancy of 2 meters “led to a request by satellite builders for coordination outside the spectrum reserved for satellites in the IARU band plans (145.800-146.000 MHz), as not enough channels are available to satisfy their requirements.”
The IARU said that, in theory, satellites could be programmed only to operate while orbiting above their countries of origin, but “because satellite orbits make it difficult to pinpoint operations, spillover to other regions may occur during parts of the orbit. Accordingly, IARU will not coordinate frequencies for satellites which are planned to operate outside the internationally aligned IARU band plans for amateur satellites.”
The IARU statement noted that its frequency coordination service aims to “maximize spectrum utilization and avoid possible interference to other satellites and ground stations.” The IARU recommended that satellite groups “work on a sharing plan or use other parts of the Amateur Service spectrum designated for satellite operation,” and it suggested resurrecting 10 meters — once popular as a satellite band, but largely unused today — as one possibility for uplink channels.
“The band segment 29,300-29,510 MHz has been used for Amateur-Satellite downlinks for more than 40 years, beginning with Australis-OSCAR 5 in 1970 and AMSAT-OSCAR 6, AMSAT’s first communication satellite, in 1972,” the IARU statement noted. Just one amateur satellite actively uses a 29 MHz downlink — AMSAT-OSCAR 7, launched in 1974. Conceding that 29 MHz downlink frequencies “would not be practical for today’s very small satellites” due to antenna size considerations, the IARU said the band could be used for uplinks, even with small receiving antennas, because Earth stations can run sufficient transmit power to overcome the disadvantage. “The IARU Satellite Adviser and his panel believe that the 10 meter band offers a good alternative to 2 meter uplinks,” the IARU said.
AMSAT President Barry Baines, WD4ASW, said his organization’s Advanced Satellite Communications and Exploration of New Technology (ASCENT) initiative is exploring alternatives to address the proliferation of CubeSats and the resulting pressure on 2 meters and 70 centimeters. He pointed out that the 200 kHz IARU allocation on 2 meters “is not very wide” given the number of satellites being launched, but the use of 10 meters is impractical in this era of CubeSats.
“It is incumbent upon the Amateur-Satellite community to develop new ways of ‘keeping Amateur Radio in space’ that take advantage of other bands and provide enhanced services through appropriate technologies, given the need to find suitable bandwidth for an increasing number of satellites,” Baines told ARRL. He said using digital technology could provide multi-channel capability, and design work is already under way. Transitioning to “underutilized amateur spectrum on bands such as 5 GHz and 10 GHz is also a possibility, Baines added, although he was quick to point out that AMSAT does not intend to abandon use of 2 meters and 70 centimeters for its own satellite projects.
The IARU said that when a large group of satellite sharing the same band is launched, “they will soon drift apart which enhances the opportunity to share the same frequencies. For example, during the initial phase, just after launch, a time-sharing system could be used to monitor the payloads before initializing transponders and other systems.”
“Currently the IARU team also coordinates frequencies for satellites built by universities and educational groups in an effort to maximize spectrum utilization and mitigate any possible interference to Amateur Radio operations,” the IARU statement concluded. “The IARU is committed to work with these groups and with the ITU to find other spectrum for these satellites.”